Transmission



June 20, 1950 P. ORR 2,512,036

TRANSMISSION Filed May 22, 1947 3 Sheets-Sheet 1.

June 20, 1950 P. ORR 2,512,036

TRANSMISSION Filed May 22, 1947 's Sheets-Sheet 2 June 20, 1950 P, ORR 2,512,036

TRANSMISSION Filed May 22, 1947 3 Sheets-Sheet 3 Patented June 20, 1950 TRANSMISSION Palmer Orr, Muncie, Ind., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application May 22, 1947, Serial No. 749,858

1 Claim. 1

This invention relates to change-speed transmissions and has as its general object to provide a transmission of the countershaft type for motor vehicles.

Another object of the invention is to provide an improved change-speed transmission of the type indicated and which will provide for variations in the speed of the drive in a forward direction and a reverse drive, yet which is axially compact.

A further object of the invention is to provide a four-speed transmission employing a minimum number of gears and which is simple and compact in construction and arrangement of parts and quiet in operation.

My invention contemplates the provision of a novel transmission having four forward speeds and reverse drive and wherein synchronizers are used with constant mesh gears for effecting second, third and fourth speeds and shiftable gears are instrumental for establishing low speed and reverse drives, the constant mesh'gears having helical teeth to insure quiet operation of the transmission and the shiftable low-speed and reverse gears having spur teeth to permit easy intermeshing engagement of the gears in the initiation of these drives from a normally inoperative condition of the transmission.

Other objects, the advantages and uses of the invention will become more apparent after reading the following specification and claim, and after considering the drawings forming a part of the specification and wherein:

Fig. 1 is a longitudinal sectional View drawn diagrammatically of my novel transmission;

Fig. 2 is a sectional view of the transmission which is taken on the line 22 of Fig. 4;

Fig. 3 is a sectional view of the gear shifting arrangement of the transmission and which is taken on line 33 of Fig. 2;

Fig. 4 is a sectional view taken along the line t-4 of Fig. 2;

Fig. 5 is a, sectional view taken along the line ti -5 of Fig. 2;

Fig. 6 is a sectional view taken along the line i6 of Fig. 2 and illustrating the friction and positive clutch arrangement of a synchronizing mechanism of the transmission;

Fig. '7 is a fragmentary view illustrating schematioally the position of the friction and positive clutch arrangement of Fig. 6 when the power transmitting members are in a synchronous rotation, said view being takenon line 'i-l of Fig. 6; r

' Fig. 8 is a fragmentary view illustrating sche- 2 matically the same parts in the intermeshing position of the positive clutch elements when the transmission members are in synchronous rotation; and

Fig. 9 is a diagrammatic view showing the path the shift lever takes to obtain the various gear ratios and neutral.

Like characters of reference designate like parts in the several views.

Referring now to the figures of the drawings, the illustrated transmission may be seen to comprise an input shaft til, an output shaft l l and a countershaft i2 mounted in a housing or casing i3. The front wall of the housing carries a suitable bearing for the enlarged end M of the driving shaft It, which may be the vehicle clutch shaft, driven from an engine through conventional clutch mechanism, not shown. The enlarged end it of the shaft Ii! is formed with an axial recess for the reception of roller bearing means [5 in which the reduced forward end Iii of the output shaft it is journaled. The rear end of the output shaft i i is journaled in a bearing it supported in the rear wall of the housing 13. The countershaft i2 comprises the gear cluster in the form of a hollow spool mounted to rotate on its arbor Z9 supported at its ends by the front and rear walls of the transmission casing. The hollow spool l2 comprises a gear cluster being formed with a number of integral gears 2|, '22, 23 and 24 and is rotatably mounted on said arbor 26 by means of the roller bearings 26, 26. The gear 2! is in constant mesh with a gear or pinion 2'? formed on the enlarged end [4- of the shaft M3,.so that the countershaft I2 is constantly connected. to and driven from the shaft Ill in well-known manner. The gear 22 is also constantly in mesh with a gear 28 which is mounted for rotation relative to the output shaft It. The gear 23 is in constant mesh with a gear 25 rotatably mounted on the shaft H. Gear 2 of the cluster isjadapted to engage with a gear 29 splined to the shaft H and movable indicated at 34 for rotative movement therewith and axial sliding movement relative thereto. The clutch mechanism 32 comprises a hub 35 fixed to the shaft H and a, collar 38 slidably disposed on the hub. The hub 35 is provided with teeth 31 on its periphery which are in mesh with teeth 38 formed on the internal surface of the collar 35. Teeth 39 and 4!! are provided respectively on the gear 21 and 28, and the collar 33 is movable from its neutral position in which it is shown in the drawings either to bring its teeth 38 into mesh with the teeth 33 in one position or to bring its teeth 38 into mesh with the teeth 43 in another position. In the former position, the engaging teeth 33 and 39 function to connect the shaft Ii) and H through the collar 36 and hub 35 and in the latter position the teeth 38 and 65 function to connect the gear 28 with the shaft l I through the collar and hub.

A blocker synchronizing ring 4! is provided between the hub 35 and the teeth 39, and a similar ring 42. is provided between the hub and the teeth 40. These rings are adapted to bear on friction surfaces 43 provided on the shaft if and on thegear 28 adjacent the hub 35, as shown. The rings ll and 42 each are provided with blocker teeth 44 which function to block the movement of the teeth 38 on the collar 36 when the teeth 44 are in the path of movement of the teeth 38. The synchronizing rings 4! and A2 are acted on by thrust bars 45 disposed in suitable slots 35 in the periphery of the hub 35. Each of the thrust bars is provided with a projection 4? which fits in a suitable internal groove in the collar 35 in the neutral condition of the clutch mechanism in which it is illustrated, and springs 48 acting on the thrust bars 45 yieldably hold the thrust bars with their projections within this groove. Each of the rings M and 42 is provided with a slot 49 receiving an end of a thrust bar 45, and the slots are of such width that the synchronizer ring may have a limited rotary movement with respect to the thrust bars. At the limit of the movement between one of the synchronizing rings and the thrust bars, the teeth 53 of the rings function to block movement of the collar 36 toward an engaged position. The synchronizer rings 4! and 42 function due to their frictional contact with the tapered surfaces 33 to synchronize the speed between the collar 33 and either the shaft H1 or the gear 23 prior to engagement of the collar either with the gear teeth 39 or the teeth 40. The thrust bars 45 function to transmit force from the collar 35 to either of the rings M or 42 to provide the synchronizing force between either of the rings and the corresponding tapered surface 43. The teeth 43 on each of the rings function to prevent a complete movement of the collar 36 to engaged position until the speed of the teeth to be engaged are synchronized with the collar and there is a slight reversal of relative rotation whereby the synchronizer ring and the teeth 44 are rotated partly to move the teeth 44 out of the path of movement ofthe teeth 38 of the collar 36. The projections 4'! of the thrust members 45 are moved out of the internal groove in the collar 33 against the action of the springs 48 when the collar 35 moves into either of its fully engaged positions. As is apparent from an'inspection of the construction, the force exerted on the rings ti and 42 from the collar 35 for synchronizing the engaging parts of the positive clutch is transmitted through the projections 41, and when these projections move out of the internal groove in the collar 36, the

.mounted on the output shaft Ii.

thrust bars do not thereafter exert synchronizing force on the synchronizer rings. The construction and operation of the clutch mechanism 32 is believed clear from the above explanation; however, the patent to S. 0. White et al., No. 2,221,900, issued November 19, 1940 may be referred to for a more full description of the synchronizer and blocker clutch mechanism.

The clutch mechanism 33 for connecting the gear 25 to the output shaft I I comprises a positive dog or tooth clutch element 56 rigidly secured to the side of the gear 23 and a positive cooperating dog or tooth clutch element 5! rigid with and extending laterally from the gear 25 rotatably The clutch member 5! is equipped with internal gear-like teeth 52, while clutch element 50 is provided with counter-part external teeth 53 adapted to fit within the cavity of clutch element 5! with its clutch teeth interlocking with the internal clutch teeth 52. When said clutch elements 53 and are so interlocked, conditions are established for driving the gear 25 from the gear 23 whereby the gear 25 will eifect rotation of the gear 29 and the output shaft H. As shown in Fig. 6, the teeth 53 are not continuous around the clutch element 59, but are arranged symmetrically in a plurality of segmental batteries or groups separated by grooves or spaces 54. The clutch teeth 52 and 53 are preferably relatively fine and numerous, and their leading ends are double inclined or tapered as at 55 to provide for intermeshing with as little clashing as possible. Clutch element Si is formed with an exterior convex conical friction clutch surface 53. A friction clutch element 51, which is illustrated as a friction clutch drum, is provided with an internal conical friction surface 58 adapted to be engaged frictionally with the conical surface 56 of the clutch element 51 The clutch drum 5'! may have a bronze clutch shoe on which the internal conical surface 58 is formed and the drum may be pressed from sheet steel with a fiat bottom 53, the central portion of which is removed to form a central opening so that the drum may engage over and surround the splined shaft H. The drum is provided with one or more radial lugs 35 extending inward from the periphery of the central opening and entering into one or more of the grooves between the lands of the splined shaft. Lugs 3%! are of less circumferential extent than said grooves, as shown in Fig. 6, and provide for a positive driving connection between the splined shaft l i and the clutch drum and also for a limited relative rotary or angular movement. The radial lugs iiil are disposed between the spaces between the groups or batteries of teeth in the toothed coupling element 53, and the portions of the drum between the lugs 69 are formed with internal taperedteeth 62 adapted to mesh with teeth 53 on the clutch element 53 on axial movement of the gear 29. Because of the described construction of the drum, the batteries of teeth 53 may pass between the radial lugs 60 to engage the teeth 52 of the drum and thereafter to engage the companion teeth of the other clutch element 5i when synchronous speeds of the two clutch elements have been attained.

The clutch drum 5! mayhave a limited axial movement sufiicient to permit the conical friction surfaces to be pressed into driving engagement and be released. This movement is preferably very slight as it is desirable to have the internal conical friction surface of the drum ride (5 on the oily external cooperating conical surface of the mating element when the clutch element 50 is in neutral for a reason that will presently appear. A stop ring 6| limits the retreat of said drum from inter-engaging position so that the conical surfaces separate only far enough to allow them to ride one on the other with an oil film in between. V

The ends of the teeth 53 of the clutch element 59 are preferably substantially parallel, when in contact with the inclined end faces of the adjacent teeth 62 of the drum to co-act with these teeth, so that if the gear 29 is forced axially into contact with the drum, the force acting axially will be resolved into two forces on the drum, one of which is tangential to the circle in which the drum revolves. relative to the splined shaft of which the drum is capable is sufiicient to bring the teeth 62 thereon and the teeth 53 of the element 59 into axial alignment when the drum is at one or the other extremities of its said relative rotary movement. As long as there is any differential rotation between the shaft H and the shaft ID, or between the shaft H and the gear 25, the drum inasmuch as it is always in frictional contact withgear 29 by reason of the oil film between the mating conical surfaces, will be dragged to one extremity or the other of its possible rotary movement on the spline shaft so that upon axial movement of the gear 29 under such conditions, an axial thrust upon the clutch element 59 will press the friction surface of the drum 5? into firm contact with its companion friction surface 56 on the element 5|. Upon axial movement of the gear 29 and the clutch element 56, the inclined surfaces on the teeth 62 of the drum will be forced axially against the corresponding surfaces 55 of the teeth of the clutch element 59. The force applied to oppose further advance of the clutch element 59 toward intermeshing position will then depend upon thetangential force due to the inertia of the gear 29, the counter shaft gears, and the input shaft l9. If this force is greater than the operator can overcome he cannot intermesh the two clutch elements. The pressure he applies in endeavoring to overcome tangential force presses the friction elements together; when the pressure is sufficient to bring the gear 25 and the output shaft ll substantially to equal speeds the tangential force disappears and continued pressure upon the gear 29 can then displace circumferentially the gear 25 and its element 5| owing to the inclination of the teeth surfaces,

permitting-the teeth of the positive clutch elements to slide together, as shown in Fig. 8. The construction and operation of the clutch mechanism 33 is believed clear from the above explanation; however, the patent to G. A. Thompson,No. 2,022,095, issued November 26, 1935, may be referred to for a more full description of the synchronizer and blocker clutch mechanism.

- Four speeds in forward drive and a single speed in reverse drive are provided by the illustrated transmission. Lowspeed forward drive is provided by moving gear 29 axially of the shaft II to engageits teeth with the teeth of the gear 24 of the countershaft gear cluster. The drive is then. from the drive shaft I9 through the gears 2'! and. 2| and the gears 24 and 29 to the driven shaft |,|.1 Second speed in forward drive is pro vided by moving gear 29 axially of the shaft II to. engage the-teeth 53.013v its clutch element 59 with theteeth. 52 of the clutch element 5| of the gear 25 vto-therebyconnect gear 25 in driving,

The extent of rotary movement relation with the shaft II. It may be noted that the gear 25 is in constant mesh with the gear 23 of the countershaft which is constantly rotated during forward drive through the trans,- mission, and due to the difference of the di-v ameters of the meshing gears 23 and 25 and the rotation of the meshing gears 24 and 29 in first speed, the gear 25 will be rotated at a speed different than the gear 29 in first speed so that it is desirable to afford a synchronizing mechanism between first and second speed drives in order to synchronize the speed of the gears 29. and 25 prior to the engagement of their clutch elements for second speed to. avoid clashing. The power train in second speed is from the drive shaft I0 through the gears 21 and 2| and through the gears 23 and 25 and the clutch mechanism 33 and gear 29 to the driven shaft Third speed forward drive is provided by moving the clutch collar 36 to the right (Fig. 2), to engage it with the teeth 49, the clutch mech; anism 33 being disengaged. The drive in third speed forward is from the shaft l9 and through the gears 21 and 2| and through the gears 22 and 28, the clutch mechanism 32 to the driven shaft ll. Fourth speed forward drive constitutes a direct drive between the shaft l9 and H is completed by moving the clutch collar 35 to the left into engagement with the teeth 39. Reverse drive is obtained by shifting the clutch mechanisms 32 and 33 to neutral conditionand thereafter shifting the gear cluster including the reverse idler 3| into mesh with thegear 29 and the gear 3|a into mesh with the gear 24 of the, countershaft gear cluster. In reverse drive, the power train proceeds from the drive shaft in through the gears 21 and 2|, the gear 24, the gear Ella and the associated gear 3| which is in mesh with the gear 29 and then to the driven shaft I It may be noted from a consideration of Fig. 2 that the pairs of constant mesh gears 2|-2"|,, 22-29 and 2325, are formed with helical teeth which are instrumental in insuring quiet operation of the transmission and that the gears 24, 29, 3| and 3| a are provided with spur teeth so that intermeshing of the teeth of the slidable gears with the other of these gears in establishing low speed and reverse drive is obtained with a minimum of effort by the driver.

The mechanism for shifting the clutch sleeve 36, the gear 29, and the gears 3| and 3|a for conditioning the transmission for the various forward speed ratios and reverse drive will now be described. Yokes 10, H and 12 are provided and which fit respectively into suitable grooves formed in-the gear 29, the sleeve 36 and the idler gear set 3| and 3| a so that the yokes may shift these parts. The yokes 19,. 1| and 12 are respectively fixed to shafts 13, 14 and I5, and these shafts are slidably disposed in space walls i6 and 16a in the transmission case cover generally designated 11 as will be apparent from an inspection of Figs. 3 and 4. As shown and i5. The shaft 13 is provided with three notches-t2, t3 and 8t;. the shaft '14 is provided with three notches 85, 88, 81; and the shaft provided with two notches 88 and B9. The notches-82 B3 and are adapted to cooperate with a ball 80 'slidalcly disposed in a cylindrical cavity-lil provided in 'thewall 1 811. The ball 90 is acted on by :a-spring 92 disposed in the cavity SI and held in place therein; The notches 85, and 81-a-r'e adapted to-co'operate with a hall 93 which is disposed in another cavity 34 in the wall 16a nfthecaseoover I1 and which is acted on :bya spring 95, Axball 96 is provided for cooperating with the notches '88 and $9., and the ball 96 is disposed in another cylindrical cavity STLin sa-i'd wall of. the case cover I 1, said ball: 95 being acted on :byi a spring 98. The halls 90. 93 and 98 all act similarly with respect to their respectivenotches in the shafts 13, 14 and 15' and function' as detent means for yieldably holding thesha'ft-in a'inumber oi difierential positions.

The notches 82, 83 and 84 in the rail I3 are so disposed thereon that the :hall 96 when in the notches functionr to'yieldably hold the .gear 29 respectively in its firs'tv'or low speed drive position wherein the gear 29 meshes with the .gear 24', in neutral position in which the gear ill-usti'ated or in second speed position in which the 'clntchte'eth -53 -of the clutch element 58 connected to thelgea'r are in mesh with the teeth :32 of the clutch element. '51 connected to the gear 25. The notches 85, Hand 81 are so disposed on the shift rail T4 that the hall 93 when in the notches functions to yielda'bly hold the clutch sleeve 36 respectively in its third speed position which the sleeve is in engagement with the teeth $0,111 neutral position, in which the sleeve is illustrated, "or in the direct drive position of the sleeve in which it is engaged with the teeth 39. The notches B8 and 89 in the shaft 4 'I51a're sord fs'pbsedin said shaft that the ball 96 inneti'onsrespectively to yieldably hold the idler gears 31 31:11 'eitherin their neutral positions in which they ai'e'illus-trated 'or in their reverse speedspositions in 'whichthey are engaged with tl'zegeetts flandw.

I i he mechanism for locking the "rails 13, T4 and 15 --againstvmovement under certain conditions Icomprises'amotch M8 formed in the rail f3; notches I8-I and' l'ifl :formedthe rail I4, and a notch I-Il3 formed in the rail "I5 and an Interlocked element or been flit is provided in a cylindrical cavity 1:35 extending between the notches 168 and WI, and another interlock element I06 is provided in a cylindrical cavity Iill extending be'twen'the notches H12 "and H33. A pin W8 is slidably disclosed in the rail "Ill and extends net-ween the slots II! I "and H32.

= It will be'noted'that, in the drawings, the rails 13, I4 and 75 are" illustrated in their neutral positions, and the notches "-IT00'to T03 inclusive are all in-line "with each other and with the interlock elements I'G'flahd lllfi and pin IGB in these positions of the rails. The interlock elements 'I-G iand me and the pin I03 function to prevent amovemen-t of "two of the r'afls out of their neutral positions *when a third rail is moved out of neutral position. "This locking niech'anism' thus 'functions'to prevent a 'conc'litioning of the transmission into more than one speed ratio at a time. Inthe 'iorm chosen for illustration, the interlock elements I04 and tilt each comprise theusua'l -beans and referring to Fig-is, each interlock'el'ement m4 and H16 is of 8 x-- 1 I is seated in one of the. notches, notch .IIlI :ioi example, its-opposite end. is able. to ride out of the opposite notch Hi0 on the outer surface of the trail. 13, the element JIM thereby being urged intothe notch rIIlI .in the .rail I4 and to move the pin I68 and thereby the element Illli into the notch I03 in the rail 15,vwhereby the rails 34 and H5 will :be prevented from moving. Similarly the. interlock provided between the shafts 1'4 and I5 isisuch that when the interlock element I 06 is disposed in the notch H12 in the rail 14 to prevent (movement of. said rail, the other end will be disposed out of the opposite notch in the rail Hi3 and will ride upon the surface of the latter rail to permit shifting movement thereof, this movement of the element I06 moving the pin IE8 whichactuates the element I04 into thenotch I110 :in the rail 1-3 to prevent shifting movement thereof.- To prevent shifting movement of the rails 73 and IB dnning that of the rail M, the shiftin of the rail 14 will cause the elements M4 and N36 to be moved into the notches 1G0 and 163 respectively, in the rails 53 and T5 to restrain the latter vrails 7 3 and 15.

To actuate :thezgear shit-trails I3, '14., 15, to obtain the different for-ward speed ratios and reverse drive, a gear shift lever l IiI is mounted for universal movement in a socket III provided in a hollow conical upstanding pedestal or riser -I I2 of the transmlssion'case cover TI. The lever -I I0 is provided with a ball-1H1 in spherical engagement as at I I4 with thewall of the socket I II and is urged against said wall by a spring II Ia having one end seated against the ball and its other end abutting a plate II 5 having a-p'eripheral flange in spherical engagement as at IIfia with the upper end of the riser I I2, the aforesaid arrangement universally mounting the lever H0 in the transmission case cover TI. The lower end of the lever M0 is adapted tocooper-ate with suitable blocks -or arms M6, III, I I8 secured to the rails l3, l4 and 15 and having notches at .'I I 9, I20 and IN therein, normally arranged in alignment for ooacting with the finger I-22 'attheen'd'oi the lever II'B. It will be apparent that the lever I-III may have lateral movement 'for selecting a desired rail to Ice shift-ed and also a selecting foreand-aft movement iorshi-fting the selected rail.

Referring to Figs. '3 and 5, it will be observed that when finger Ill-2 of lever 'I I0 engages in notch I2-0 for shifting the=-rai1 14., the thirda'nd fourth speeds may be obtained :as previously related. In such position, thelever I I'll-is adapted to be thrust against a spring 'pressedq-plunger I23 slidably mounted a cylindrical cavity I24 in the block H8 fixed to shift rail; and extending into the notch l2I in said block" ilt maybe noted that the plunger 12 3 is o l-- piston-like form with the reduced portion I-2ii thereof extendingthrough the rear wall hf the cavity Il24 and having threaded adjustable relation-with the nut I26 to'position the plunger head by the action of the spring -I2 in a desired position withrespect :to the notch I'-2=I and the finger Idiot lever 1H 0. Zine-purpose of such spring i'pressed plunger 4-23 is toindicate to the operator when the transmission is being shifted to reverse dnivef-position :as the resistance which "such spring ipressed plunger ofiers against the finger I22 'of lever I IIi requires more effort 'on the 'parto'f the operator to shift into reverse-drive position than "into theifcrward speed ratio positions.

My invention mirovi'de's'ra "very satisfactory Tourspeed transmission 'uiherein direct drive and third such length that when'the'interlock'element "I04 and 'second'speeds -can *all be introduced on synchro-mesh" principles, low or first speed being obtained by means of a sliding member, shown in the drawing in the form of a sliding gear, without the use of any synchro-mesh feature, as a change down to this speed while the caris moving is, in practice, seldom necessary.

While I have described my invention in connection with one specific embodiment thereof it is to be understood that this is by way of illustration and not by way of limitation and the scope of my invention is defined solely by the appended claim which should be construed as broadly as the prior art will permit.

I claim:

In a transmission, a casing, aligned driving and driven shafts mounted in said casing, a countershaft mounted in said casing, a plurality of gear trains including, in the order named, a first gear train for transmitting a drive from said driving shaft to said countershaft and second, third and fourth gear trains for transmitting forward drives of varying speed ratios from the countershaft to the driven shaft, clutch means interposed between the first and second gear trains and including a clutch sleeve connected to and shiftable axially of said driven shaft selectively engageable with clutch elements respectively connected to the drive shaft and to a gear of the second gear train, means forshifting said clutch sleeve and including a shift rail connected to said clutch sleeve, said third gear train comprising a gear axially fixed and rotatable on said driven shaft and said fourth gear train comprising an axially shiftable gear drivingly mounted on said driven shaft, coupling elements respectively driven from said gears and adapted to drivingly connect said gears in response to shift of said axially shiftable gear, means for shifting said axially shiftable gear to connect said shiftable gear with said fixed gear of the third gear train or into meshing engagement with a countershaft gear for selectively connecting the driven shaft to the third gear train or to the fourth gear train and including a shift rail connected to said shiftable gear, means for rotating said driven shaft in a direction reverse to the direction of rotation of said drive shaft including a reverse gear cluster comprising an idler shaft, a pair of gears loosely mounted on said idler shaft and shiftable into mesh with said shiftable gear and the countershaft gear of said fourth gear train, and means for shifting said reverse gear cluster including a shift rail connected to said cluster, said shift rails being slidably mounted in a horizontal plane in spaced walls in said casing with said rail for shifting said clutch sleeve being disposed between said rail for shifting said axially shiftable gear and said rail for shifting said gear cluster, each of said rails having a neutral position, and an interlock de- 10 two bean-like elements slidabl carried in an elongate passage formed in one of said walls and extending transversely of said rails, one of said elements being disposed between said gear-shifting rail and said clutch sleeve-shifting rail and the other element being between said gear clustershifting rail and said clutch sleeve shifting rail, each of said gear and gear cluster-shifting rails having a notch therein adapted to receive the adjacent element and said clutch sleeve-shifting rail having notches in opposite sides thereof re ceiving one or the other of said bean-like elements, under certain conditions, a pin slidably carried by said clutch sleeve-shifting rail and having its opposite ends extending into the notches therein and abutting said elements, a

manually operable gear shift lever projecting into said casing from the exterior thereof, means piv-' otally mounting said gear shift lever in said casing at a point medially of its ends for universal swinging movements, a block secured to each of said; shift rails, there being a notch formed in each of said blocks designed for selective reception of an end of said gear shift lever therein, the block carried by the shift rail which is connected to the reverse gear cluster being formed with a bore therein communicating with the notch in said latter block, a piston-like blocking element slidably disposed in said bore and extending into said latter notch, and yieldable means normally urging said piston-like element to a position wherein it yieldingly blocks entry of the end of said gear shift lever into the notch into which it extends whereby a greater manual effort on the part of an operator is required to move said gear shift lever so that the end thereof enters said I last-mentioned notch than is required to move vice positively restraining shifting of two of said 00 rails from their neutral positions upon shifting of the other of said rails to establish one of said forward drives or said reverse driv and comprising said gear shift lever so that its end enters either of said other notches.

PALMER ORR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,564,719 Sponable Dec. 8, 1925 1,973,807 Grinham et a1 Sept. 18, 1934 2,015,736 Vandervoort Oct. 1, 1935 2,193,672 Dolza Mar. 12, 1940 2,256,320 Lapsley Sept. 16, 1941 2,300,036 Peterson Oct. 27, 1942 2,368,868 Orr Feb. 6, 1945' 2,428,892 Plexico Oct. 14, 1947 FOREIGN PATENTS Number Country Date 405,214 Great Britain Feb. 1, 1934 190,669 Germany Oct. 30, 1907 OTHER REFERENCES Publication, Automobile Engineer, issue of November 21, 1946, pages 535-538. 

